HIV/AIDS
(Human Immunodeficiency Virus · AIDS)
In this condition factsheet:
The Facts on HIV/AIDS
AIDS (acquired immune deficiency syndrome) was first recognized in North America in the early 1980s. It is caused by a virus known as HIV (human immunodeficiency virus). HIV infection has become a worldwide epidemic. The World Health Organization estimates that since its discovery, it has caused over 40 million deaths worldwide, and approximately 38 million people are living with AIDS. It is estimated that around 63,000 people live with HIV in Canada, and of these people, about 10% have not received a diagnosis.
HIV is more common among certain populations, such as men who have sex with men, and people who inject illicit drugs. The infection is also more common among socially disadvantaged communities.
Causes of HIV/AIDS
The virus can be found in the blood, semen, vaginal fluid, and breast milk of infected people. HIV is also found in saliva, sweat, and tears, though not in high enough amounts to transmit the virus to another person. HIV does not transmit through sneezing, shaking hands, or from toilet seats or mosquito bites.
The 2 most common ways to be infected with HIV in North America are through unprotected sex and sharing needles. HIV may be transmitted through unprotected vaginal, anal, or oral sex. Although the risk of infection is lower with oral sex, it is still important to use protection during oral sex, such as a dental dam (a piece of latex to cover the vagina during oral sex) or a condom. HIV can also be passed on through perinatal infection, where mothers who have HIV are at risk of giving the disease to the baby during birth. The risk of perinatal infection is declining with new treatments. Breast-feeding by an infected mother can also transmit HIV.
Once HIV enters the bloodstream, it takes over cells vital to the immune response, known as CD4+ lymphocytes. The virus then inserts its own genes into the cell, turning it into a miniature factory that produces more copies of the virus. Slowly, the amount of virus in the blood goes up and the number of healthy CD4+ cells goes down. The destruction of CD4+ cells interferes with the body's ability to fight off infections, cancers, and other diseases.
Symptoms and Complications of HIV/AIDS
Symptoms of HIV infection appear 2 to 12 weeks after exposure. At this point the virus begins rapidly taking over immune cells in the blood. The symptoms of this phase are flu-like and include:
- diarrhea
- fatigue or weakness
- fever
- headache
- joint pain
- night sweats
- rash
- swollen glands
- weight loss
- yeast infections (of the mouth or vagina) that last a long time or occur frequently
When the symptoms begin to appear, the person with HIV is very infectious. The symptoms usually go away within a week to a month, and the person will feel fine again. However, the symptoms may return from time to time. The symptoms of HIV are similar to symptoms of other viral infections. The only way to know for sure whether you are HIV-positive is to be tested. After infection with HIV, it takes approximately 3 weeks for antibodies to the virus to be detectable in the blood, although for some people the antibodies are not detectable for up to 3 months. The period during which antibodies develop and appear in the blood is called seroconversion. After seroconversion, the virus can be detected using a blood test.
After the initial symptoms go away, the body's immune system tries to control the virus. The immune system can keep the virus at bay for a while, but it can't completely get rid of it. Many people will feel fine for years before their immune system weakens and they develop AIDS. Without treatment, about half of HIV-positive people develop AIDS within 10 years of infection. Some people develop AIDS within a few years of infection. A few, called long-term non-progressors, do not develop AIDS until much later. Rarely, some individuals termed "elite controllers" can control the virus for decades and appear never to develop AIDS. Many factors affect the timeframe to develop AIDS, including medications, genetic inheritance, the aggressiveness of the virus, and the person's general health and lifestyle.
AIDS is a term applied to the most severe form of HIV infection. AIDS is defined as having HIV and a specific type of infection ("opportunistic" infection) often associated with AIDS. These infections can be bacterial, fungal, viral, or parasitic. Examples of opportunistic infections include toxoplasmosis, Pneumocystis jerovicii pneumonia, cryptococcal meningitis, progressive multifocal leukoencephalopathy (PML), cryptosporidium, cytomegalovirus, and Mycobacterium avium complex (MAC). With the use of better medications to treat HIV, the risk of opportunistic infections has dropped dramatically over the years; however, people with AIDS will usually need to take medications (such as antibiotics) to prevent opportunistic infections.
People who have AIDS and receive no treatment are also more likely to develop cancer, especially cancers of the immune system (lymphomas). Another cancer common for people with AIDS is Kaposi's sarcoma, a type of cancer that causes bluish red nodules on the legs and that spreads to the lymph system. Women with AIDS are prone to developing cancers of the cervix. Men who have sex with men, that have HIV have higher rates of infection by human papillomavirus (HPV), a virus linked to anal cancer.
Children with AIDS tend to get common childhood infections like conjunctivitis, otitis media, and tonsillitis, but they experience symptoms much worse than the infection usually causes.
Excessive weight loss or "wasting syndrome" is a problem for approximately 20% of people who have HIV infection. It is associated with an unexplained loss of 10% or more of normal body weight plus chronic diarrhea (30 days or more) or chronic weakness with fever (30 days or more).
Most people with AIDS die from the diseases that AIDS makes them more susceptible to. The virus occasionally infects the brain, causing dementia that gets worse over time.
